As will be appreciated, tailgates for pickup trucks typically range in weight from 40 to 70 pounds and are hinged at the rear of the truck bed such that when the tailgate is unlocked by the pulling of a lever or handle, the tailgate opens to a point level with the truck bed where it is restrained usually by detachable folding straps. Typically, the tailgates can be removed from the truck body when the tailgate is pivoted to a partially open tailgate removal position.
The weight of the tailgate precludes one handed operation for any but the strongest individual. People of normal build have to use their second hand, or shoulder or knee to support the tailgate in an effort to kept it from dropping too quickly.
The single-handed supporting of the tailgate often times can result in wrist injury as the weight of the tailgate overpowers the ability of the individual to control its descent and it comes crashing down in an uncontrolled fashion. Normally a person drops the gate or sometimes raises his or her knee in order to arrest the fall of the tailgate.
The raising of one's knee to prevent the tailgate from dropping has reportedly resulted in crushed knee caps or other damage to the knee, whereas supporting the relatively heavy tailgate through one handed operation has resulted in sprained wrists due to the inability of the individual to hold the heavy tailgate with one hand.
It will be appreciated that a free falling tailgate can, in fact, crush anything that is underneath it and can, for instance, hurt children who are standing at the back of the tailgate when it falls. Moreover, it is hard to close a heavy tailgate.
Note that pickup trucks and vehicles with tailgates are now more popular in suburban settings in which the tailgate is to be lowered, for instance, to load groceries into the back of the pickup. Pickups are also utilized routinely in camping and the provision of camper tops for the pickups has increased their popularity for carrying lighter loads than a pickup is normally designed to carry. This popularity has resulted in the use of these trucks by non-professionals such as family members and indeed anybody associated with the family. Thus, it is important that the tailgate be counterbalanced in such a way that it not cause damage to one trying to lower it and must afford the ability to close the tailgate in a single handed operation easily even by a small person, yet permit rapid removal of the tailgate and the counterbalance mechanism from the truck body.
In the past, tailgates have been counterbalanced by internal torsion bars which are factory installed such as illustrated by U.S. Pat. No. 5,358,301. Since these counterbalancing mechanisms are only installed in a limited number of vehicles, there is a necessity for providing an after-market device to be able to counterbalance the tailgate.
As illustrated by U.S. Pat. No. 5,988,724, issued to Tiete O. Wolda, a torsion bar or torquing device called a torque rod is utilized in the tailgate hinge mechanism such that the tailgate has a torque rod which assists in the opening or closing of the tailgate. While the Wolda patent indicates that his device is suitable for after-market installation, it requires the removal of the hinge bracket, which previously was bolted to the truck's tailgate. However, presently, the hinge brackets are often spot welded to the tailgate, making after-market utilization impossible.
In an effort to address the after-market, there are those who have tried to use coil springs to counterbalance tailgates. However, coil springs are much too cumbersome and unsightly to be attached to tailgates. One such attempt to use coil springs is illustrated by U.S. Pat. No. 5,954,383, in which a spring-loaded pulley arrangement along with a tether is utilized to assist in the lowering and raising of a tailgate. However, such a lift kit involves the mounting of a channel that houses the pulleys and a sizable spring which obstructs the loading area and is so big that it is difficult to merchandise, for instance on a rack display. Moreover, the device is cumbersome to install and is unsightly.
There is thus a need for an extremely compact easy to attach a counterbalance device that can be hidden from view and yet has the strength to provide the required counterbalance force.
By way of further background, there are a number of devices, which limit the positions of a tailgate, one of which is shown in U.S. Pat. No. 4,585,265. However, there is no counterbalancing action in such a positioning device.
Additionally, there are a number of devices, which are utilized to reduce the aerodynamic drag caused by a tailgate by partially opening it. One such device is illustrated in U.S. Pat. No. 5,645,310, in which a strap keeps the tailgate at a predetermined angle so as to minimize the aerodynamic load. Note that in this device there is no spring loading or any attempt to counterbalance the tailgate.
A further air drag reducing tailgate device is shown in U.S. Pat. No. 5,234,249 issued to Jay I. Durrell in which the tailgate is positioned responsive to the force of the wind or air pressure on the tailgate panel. This is done through the utilization of a dashpot type device in which a conventional door closure device is utilized to position the tailgate.
It will be appreciated in the above-mentioned patent that there is no attempt to counterbalance the tailgate during opening or, in fact, facilitate opening and closing of the tailgate. In this patent the spring tension is set to be responsive not to the weight of the tailgate but rather to the aerodynamic pressure on the tailgate which pressure exceeds counterbalancing forces. The reason is that not only must the weight of the tailgate be accommodated through the tensioning mechanism; it must counteract the force on the tailgate presented as a cross-section to the wind.
Wind pressures on a tailgate of 60″×20″ at 75 miles an hour exceed 150 pounds. On the other hand, the tailgate itself weighs, for instance, 50 pounds so that the tension set by the Durrell device would have to be three times that necessary for counterbalancing. The result is that with this device installed it would be virtually impossible to open the tailgate at all. As a result, the Durrell device must be disconnected in order to lower the tailgate. To this end, Durrell describes that its links can be quickly disassembled so that the tailgate can be lowered for loading of the truck. In short, although the Durrell reference utilizes a door closure apparatus for providing that the tailgate be partially opened in the presence of wind loading it does not aid in lowering and raising the tailgate to load or unload the truck.